Medical device for treating a heart valve insufficency

ABSTRACT

A medical device for treating a heart valve insufficiency, with an endoprosthesis which can be introduced into a patient&#39;s body and expanded to secure a heart valve prosthesis in the patient&#39;s aorta. In an embodiment, the endoprosthesis has at plurality of positioning arches configured to be positioned with respect to a patient&#39;s aorta and a plurality of retaining arches to support a heart valve prosthesis. The endoprosthesis includes a first collapsed mode during the process of introducing it into the patient&#39;s body and a second expanded mode when it is implanted.

This invention relates to a medical device for treating a heart valveinsufficiency, with an endoprosthesis which can be introduced into apatient's body with minimal invasion and automatically expanded in orderto position and secure a heart valve prosthesis in the patient's aorta,which endoprosthesis has at least three positioning arches forautomatically positioning the medical device in the patient's aorta anda retaining segment with retaining arches for accommodating a heartvalve prosthesis, and the endoprosthesis assumes a first pre-definablemode during the process of introducing it into the patient's body and asecond pre-definable mode in the state when the medical device isimplanted, and when the medical device is in a collapsed state when theendoprosthesis is in the first mode and in an expanded state when theendoprosthesis is in the second mode.

The operating principle of such a device is known from medicaltechnology. Biological or mechanical valve models are currentlyavailable as a means of replacing human heart valves, which are securelystitched in the heart valve base through an opening in the thorax duringsurgery once the diseased heart valve has been removed. In order toundertake this intervention, the patient's circulation must be supportedby a heart and lung machine and the heart is arrested whilst the heartvalve prosthesis is being implanted. This is a risky surgicalintervention which places the patient at risk accordingly and whichinvolves a long post-operative phase of treatment. In multi-morbidpatients in particular, the risk of carrying out such intervention is nolonger justifiable.

In more recent times, treatment methods which are minimally invasivehave been developed, which are distinctive due to the fact that theintervention can be carried out with a local anaesthetic. This option isbased on the use of a self-expanding stent with a collapsible heartvalve prosthesis, which is implanted in the human body by means of anappropriate catheter system. A self-expanding heart valve prosthesis ofthis type can be fed by means of a catheter system through a main arteryor vein to the implantation site at the heart. Once the implantationsite is reached, the stent, which is made up of several self-expandingstent segments which can be angled relative to one another, issuccessively unfolded. Once unfolded, the heart valve prosthesis can beanchored in the respective blood vessel at least in the vicinity of theheart with the assistance of anchoring hooks for example. The actualheart valve prosthesis is then disposed directly in the proximal regionof the stent or endoprosthesis.

Patent publication DE 100 10 074 A1, for example, discloses a device forsecuring and anchoring heart valve prostheses, which essentiallycomprises shaped wire elements connected to one another. In thisinstance, different arches are used as a means of reliably securing andanchoring the heart valve prosthesis. To this end, the device describedin this specification has three identical pairs of arches respectivelydisposed at a distance of 120° apart. These arches are connected to oneanother by fixed body joints, and the fixed body joints assume thefunction of pivot bearings. Arches bent in the opposite direction arealso provided, which form lever arms which are of identical length asfar as possible, to enable a reliable seating of the arches, even in theevent of peristaltic movements of the heart and blood vessel, and afforda reliable seal for an implanted and secured heart valve prosthesis.

With the known solution, however, there is still a risk of heart valvesbeing incorrectly implanted. In particular, this is attributable to thefact that the heart valve prosthesis must be exactly positioned andlongitudinally oriented. In particular, it requires enormous skill onthe part of the surgeon performing the treatment—if it is possible atall—to position a stent which has a heart valve prosthesis at itsproximal end and to do so accurately enough in the vicinity of thepatient's diseased heart valve to ensure both correct lateralpositioning accuracy and a correct longitudinal position of the heartvalve prosthesis as far as possible.

Amongst other things, incorrect implantation of a heart valve prosthesisthat is not optimally positioned can lead to inadequate sealing or valveinsufficiency, which places considerable stress on the ventricle. If aheart valve prosthesis is implanted too far above the actual heart valveplane, for example, this can cause the outlets of the coronary vessels(coronaries) to close, thus leading to fatal coronary ischaemia due toheart infarction. This being the case, it is absolutely vital that boththe lateral positioning accuracy and longitudinal positioning accuracyof a heart valve prosthesis meet requirements.

In the case of conventional implantation techniques wherebyself-expandable heart valve prostheses are fed to the implantation siteat the heart through a main artery of the patient requiring minimalinvasion, for example, the prosthesis is usually introduced by means ofa guide wire and with the aid of catheters, in which case it is standardpractice to use a balloon catheter for this intervention. Although it ispossible to monitor and control the introduction process during such anintervention, for example with the aid of an X-ray system (heartcatheter laboratory=HCL) or with the aid of ultrasound(trans-oesophageal echocardiagram=TEE), the heart valve prosthesis isstill of relatively large dimensions in spite of being collapsed whilstit is being introduced and it is often not possible to obtain therequired positioning accuracy due to restricted ability to manoeuvre,and in particular to ensure correct longitudinal positioning of theheart valve prosthesis to be implanted with the fixing elements attachedto it accordingly. Especially if there is a risk that the coronaryvessels might close, implanting the heart valve prosthesis in a positionangularly offset from the optimum implantation site represents aparticular risk for the patient.

When designing a heart valve prosthesis, allowance must specifically bemade for the considerable forces which act on the prosthesis, includingduring the filling phase of the heart cycle (diastole), and reliableanchoring is necessary in order to prevent the implanted heart valveprosthesis from becoming detached.

Accordingly, it must be possible to manoeuvre the heart valve prosthesisin the relevant access vessel as efficiently as possible during theimplantation process in order to ensure optimum positioning accuracy onthe one hand, and on the other hand, the implanted heart valveprosthesis must be firmly anchored at the implantation site in ordereffectively to prevent the prosthesis from shifting subsequently.

The underlying problem addressed by this invention is the fact thatknown devices used for the transvascular implantation of heart valveprostheses are often not suitable for implanting a heart valveprosthesis easily to the required degree of positioning accuracy.Furthermore, until now, it has only been possible to correct anincorrectly positioned heart valve prosthesis that has already beenpartially implanted with great difficulty—if at all.

Against this background, the objective of the invention is to improve amedical device for treating heart valve insufficiency of the typeoutlined above so that maneuvering of the device is optimised during theimplantation process on the one hand, and whilst achieving optimumpositioning accuracy and anchoring of the implanted heart valveprosthesis on the other hand, thereby permitting a routine treatment ofheart valve insufficiency without subjecting the patient to excessivestress.

This objective is achieved by means of a medical device of the typeoutlined above due to the fact that the endoprosthesis of the medicaldevice is of an integral structure cut from a metal tube, and every endportion of the positioning arch at the distal end of the endoprosthesisis joined to the terminal portion of the associated retaining arch.

Accordingly, a medical device is proposed which essentially comprises aself-expandable endoprosthesis (hereafter referred to simply as stent),and this stent has a valve-supporting retaining segment foraccommodating a heart valve prosthesis. The stent design is distinctivedue to the fact that at least three positioning arches are provided,which project radially outwards and are open when the endoprosthesisassumes the second pre-definable mode, in which the original (old) heartvalves of the heart valve to be replaced engage, thereby resulting in anautomatic fixing and positioning of the medical device as regards theaxial rotation on the one hand and the horizontal position on the otherhand.

Since the endoprosthesis (stent) of the medical device has an integralstructure cut from a metal tube incorporating the positioning arches onthe one hand and the retaining segment with the retaining arches on theother hand, the endoprosthesis and hence also the medical device can bemade particularly inexpensively and in large numbers. Specifically, itwould be conceivable to cut the stent structure from a metal tube bymeans of a laser, after which the structure is subjected to anappropriate shaping and heat treatment process so that theendoprosthesis and hence also the medical device can be transferred fromthe collapsed sate during implantation to the expanded state at theimplantation site. This shaping and heat treatment process isadvantageously operated in steps in order to prevent damage to the stentstructure.

Since the endoprosthesis of the medical device is of an integralstructure cut from a metal tube as proposed by the invention and aretaining arch is associated with every positioning arch and every endportion of the positioning arch at the distal end of the endoprosthesisis joined to the terminal portion of the associated retaining arch,there is no need to provide fixed body joints or similar connectingdevices. On the other hand, the endoprosthesis of the medical deviceproposed by the invention is a stent which, on the one hand, offers apositioning function due to the positioning arches with a minimallongitudinal extension and, on the other hand, offers a function ofretaining a heart valve prosthesis due to the retaining arches.

As will be seen, when transferring the endoprosthesis from the firstpre-definable mode to the second pre-definable mode by widening thecross-section of the entire stent, the retaining arches on the one handand the positioning arches on the other hand are opened out in theradial direction. The second mode of the endoprosthesis isadvantageously selected so that as the retaining and positioning archesopen up, they hit against the vessel wall of the aorta and form apositive connection with it, thereby anchoring the medical device firmlyat the implantation site.

Due to the fact that the structure of the endoprosthesis imparts aparticularly short shape to the medical device, the medical device isparticularly easy to manoeuvre in the collapsed state, which is ofparticular advantage if the implantation route to the heart valve to bereplaced leads through the arch of the aorta. The minimum length of themedical device is made possible in particular by the special structureof the endoprosthesis due to the fact that every end portion of thepositioning arch at the distal end is joined to the end portion of theassociated retaining arch, and both the positioning arch and theretaining arch extend to the proximal retaining region of the medicaldevice or endoprosthesis. The retaining segment for accommodating theheart valve prosthesis therefore lies at the proximal retaining regionof the endoprosthesis.

Advantageous embodiments of the medical device are specified in thedependent claims, especially as regards the endoprosthesis (stent).

In one particular embodiment of the endoprosthesis used with the medicaldevice proposed by the invention, every positioning arch and itsassociated retaining arch is respectively of an essentially U-shaped orV-shaped structure, which is closed towards the proximal end of theendoprosthesis. By particular preference, every positioning arch is cutfrom the material blank of the metal tube which is accommodated by theessentially U-shaped or V-shaped structure of the associated retainingarch. In this preferred embodiment of the stent structure, therefore,the respective retaining arches of the retaining segment form theproximal retaining region of the endoprosthesis and the respectivepositioning arches are of a design symmetrical with the retaining archesbut lie slightly in front of the distal retaining region of the medicaldevice. The respective distal ends of the positioning arches are joinedto the respective distal ends of the co-operating retaining arches inthe distal retaining region of the medical device or endoprosthesis.When the medical device is in the expanded state, not only the proximalretaining region with the heart valve prosthesis fitted to it and thepositioning arches disposed between the proximal and the distalretaining regions of the medical device open out, but also the joiningpoints between the respective positioning arches and retaining arches atthe distal end of the medical device, so that a radially acting force isalso applied to the vessel wall via the distal retaining region of themedical device, which further assists anchoring of the medical device atthe implantation site.

Since the medical device is in a (an expanded) state in which the distaland proximal retaining region as well as the positioning arches areradially opened out when the endoprosthesis assumes the second mode, theexpanded medical device has as shorter length than it does in itscollapsed state. To enable the length of the medical device in itsexpanded state to be set beforehand, it would be conceivable to connectthe respective distal end portions of the positioning arches to thedistal end portions of the associated retaining arches using aconnecting web extending essentially in the longitudinal direction ofthe endoprosthesis rather than directly. The length of the medicaldevice in the expanded state can therefore be adapted by selecting thelength of this connecting web accordingly. However, it is preferable,especially with a view to ensuring good maneuverability of the medicaldevice during the implantation process, i.e. when the endoprosthesis isin its first (collapsed) mode, if the connecting web between therespective end portions of the positioning arches and retaining archesis selected so that it is as short as possible.

In one particularly preferred embodiment of the medical device, theendoprosthesis has other fixing means at its distal end, which can beengaged with an introduction catheter system. In a preferred embodimentof the fixing means, it would be conceivable for the latter to have arespective anchoring eye disposed between two adjacent positioningarches, in which case the respective arms of the adjacent positioningarches on the one hand and the respective arms of the retaining archesassociated with the adjacent positioning arches on the other hand areconnected to the anchoring eye. It would likewise be conceivable for therespective arms of the adjacent positioning arches to be directly andthe respective arms of the retaining arches associated with the adjacentpositioning arches to be indirectly connected via a connecting webextending essentially in the longitudinal direction of theendoprosthesis. Generally speaking, the purpose of the fixing meansprovided on the distal end of the endoprosthesis is to accommodateappropriate mechanisms on the introduction catheter system and thesemechanisms are of a design complementing that of the fixing means of theendoprosthesis. The engagement between the catheter system on the onehand and the fixing means on the distal end of the endoprosthesis on theother hand can be released by means of an external manipulation in orderto release the medical device at the implantation site, thereby ensuringthat the medical device expands and is thus reliably anchored.Naturally, however, other fixing means could also be used.

As mentioned above, because of the special structure of theendoprosthesis, it is possible to use a self-expandable medical devicewhich is distinctive due to its short overall length in the collapsedstate, thereby ensuring improved maneuverability during the implantationprocess, whilst simultaneously affording a self-positioning function inthe pockets of the old heart valve with the aid of the positioningarches so that the endoprosthesis is reliably anchored by the proximaland distal retaining regions of the endoprosthesis pressing radiallyagainst the vessel wall in the expanded state.

As an alternative to the preferred embodiment of the medical deviceoutlined above, in which the respective arms of the adjacent positioningarches are joined directly and the respective arms of the retainingarches associated with the adjacent positioning arches are joinedindirectly to the fixing eye by means of a connecting web extendingessentially in the longitudinal direction of the endoprosthesis, itwould however also be conceivable for the respective arms of theadjacent positioning arches to be joined to the fixing eye indirectlyvia a connecting web extending essentially in the longitudinal directionof the endoprosthesis, in which case the respective arms of theretaining arches associated with the adjacent positioning arches arejoined to the fixing eye indirectly via a connecting web extendingessentially in the longitudinal direction of the endoprosthesis, and theconnecting web of the retaining arches merges into the connecting web ofthe positioning arches at the end portion of the positioning arches.Providing the respective connecting webs for connecting the arms of thepositioning arches to the fixing eye and for connecting the arms of theretaining arches to the end portion of the positioning arches offers aparticularly simple but effective way of adapting the length of theendoprosthesis to respective requirements and does so because therespective lengths of the connecting webs can be selected accordingly.

In a preferred embodiment of the solution proposed by the invention, inorder to ensure that the distal retaining region of the endoprosthesiscan be retained at the implantation site in its expanded stateparticularly reliably, the endoprosthesis is provided with fixing eyesor similar at its distal retaining region, and these fixing eyes, whichare preferably disposed between two adjacent positioning arches, arerespectively provided with at least one barb, the tip of which points inthe direction of the proximal end of the endoprosthesis. In thispreferred embodiment, therefore, the endoprosthesis is secured at theimplantation site due to the radial force exerted on the vessel wall bythe endoprosthesis and in particular by the distal retaining region ofthe endoprosthesis, but also due to the barb hooking into the vesselwall. As regards the barb, it would naturally also be possible to useother appropriate design options.

As an alternative to or in addition to the barbs, which are preferablyprovided on the fixing eyes, another conceivable way of securing theendoprosthesis reliably at the implantation site is for the respectivearms of the retaining arches of the endoprosthesis to be respectivelyprovided with an anchoring support in the shape of a bow, which projectsout from the relevant arm of the retaining arch when the endoprosthesisis in the expanded state, the tip of which points in the direction ofthe distal end of the endoprosthesis. This embodiment therefore providesadditional fixing means for the endoprosthesis and accordinglyadditionally secures the medical device to prevent it from becomingdislocated.

In a preferred embodiment of the anchoring support, it would beconceivable for the anchoring support to be of an essentially U-shapedor V-shaped structure which is closed at the distal end of theendoprosthesis or the distal end of the medical device, in which casethe distal region of the anchoring support constitutes the tip of theanchoring support and the respective arms of the anchoring support arejoined to the respective arms of two adjacent retaining arches at theproximal end of the anchoring support.

Alternatively, in another preferred embodiment, the respective arms ofthe retaining arches have continuous slots or elongate holes extendingin the longitudinal direction of the retaining arches, the purpose ofwhich is to enable and assist the expansion of the endoprosthesis fromthe collapsed state into the expanded state because these slots orelongate holes are preferably designed to permit a particularly easycross-sectional expansion of the stent (endoprosthesis) whilstsimultaneously reducing the length. Such slots or elongate holes havethe additional advantage of saving on material.

In the case of the latter embodiment in which the respective retainingarches incorporate slots extending in the longitudinal direction of theretaining arches designed to influence the shape of the endoprosthesisin the second mode, it would be conceivable for the respective retainingarches to be additionally provided with reinforcing portions whichinterrupt the slots extending in the longitudinal direction of theretaining arches and which prevent components of the retaining archesfrom projecting outwards when the endoprosthesis is in the expandedstate, which is of particular advantage in preventing explanation of themedical device.

In a preferred embodiment, the endoprosthesis has an external diameterof approximately 5.0 mm and a length of between 33.0 mm and 40.0 mm,preferably between 34.0 and 39.0 mm, and even more preferably between34.37 mm and 38.37 mm, in its first mode, which means that the medicaldevice can be introduced by means of a 21F introduction system, forexample, and heart valve prostheses with a diameter of 21 mm to 28 mmmay be used. The length specifications given above are currentlypreferred values, on the basis of which the medical device is suitablefor the majority of patients to be treated.

In order to obtain a particularly reliable anchoring of the implantedmedical device in its expanded state, the endoprosthesis is subjected toa shaping and heat treatment process during its manufacture so that whenthe endoprosthesis is in the finished state, it has a slightly concaveshape tapering in the direction of the proximal retaining region of theendoprosthesis in its second mode.

In other words, this means that the proximal retaining region of theendoprosthesis, i.e. the region to which the heart valve prosthesis isattached, has a slightly narrower diameter than the distal retainingregion. It has effectively been found that if the distal retainingregion of the endoprosthesis in the second mode has an approximately 10%to 25% bigger diameter than the proximal retaining region of theendoprosthesis, radial forces are generated at the distal retainingregion of the endoprosthesis in particular which enable the medicaldevice to be securely retained in the vessel without causing damage tothe vessel wall, and due allowance is also made for the peristalticmovements of the heart and vessel wall. The slightly lower radial forceexpended by the proximal retaining region of the endoprosthesis not onlyserves as a means of anchoring the medical device in the aorta but inparticular also opens out the heart valve prosthesis fitted on theproximal retaining region of the endoprosthesis and imparts to it areliable seal with respect to the vessel wall. Naturally, however, itwould also be conceivable for the concave shape to be more or lesspronounced when the endoprosthesis assumes the second mode.

In particular, however, it is preferable if the retaining region of theendoprosthesis has a diameter of between 22 mm and 33 mm, and preferablybetween 25 mm and 31 mm, in the second mode. This being the case, itwould be conceivable for the endoprosthesis to be made in two or moredifferently dimensioned sizes, in which case an optimum size ofendoprosthesis could be selected depending on the patient, and the exactdimensions of the endoprosthesis are adapted to the patient to betreated—starting from a pre-defined stent size—by an appropriatefinishing treatment of the endoprosthesis (stent), in particular bytempering.

In one, particularly preferred embodiment of the medical device, notonly does it have the endoprosthesis (stent) but also a heart valveprosthesis, preferably a bio-heart valve prosthesis, which is attachedto the retaining segment of the endoprosthesis by means of a thread orsimilar, in which case orifices are provided in the retaining arches ofthe endoprosthesis through which the thread or similar is inserted.Accordingly, it would also be conceivable for the heart valve prosthesisto be connected to the retaining segment of the endoprosthesisimmediately prior to the medical intervention. As a result, the medicaldevice can be made in a modular design, which is of particular advantagein terms of transporting and storing the medical device.

As regards the preferred material used for the endoprosthesis of themedical device, a shape memory material is used, which is designed sothat the endoprosthesis is transformed from a temporary shape to apermanent shape by means of an external stimulus, in which case theendoprosthesis assumes the temporary shape in the first mode (when themedical device is in the collapsed state) and the endoprosthesis assumesthe permanent shape in the second mode (when the medical device is inthe expanded state). Especially if a shape memory material such asNitinol is used, i.e. an equal atomic alloy of nickel and titanium, theimplantation process will be particularly gentle during the operation ofimplanting the medical device.

During production of an endoprosthesis made from a shape memorymaterial, after the stent structure has been cut from the metal tube, itis deformed and fixed in the desired permanent shape, a process which isknown as programming. This operation may be performed on the one hand byheating, deforming and then cooling the stent structure. Alternatively,the stent structure may also be deformed at low temperature by anoperation known as cold stretching. As a result, the permanent shape ismemorised whilst the temporary shape actually prevails. If the stentstructure is then subjected to an external stimulus, the shape memoryeffect is triggered and the memorised permanent shape is restored.

In a particularly preferred embodiment, the external stimulus is asettable switching temperature. It is therefore conceivable for theendoprosthesis material to be heated to a temperature higher than theswitching temperature in order to trigger the shape memory effect andthus restore the memorised permanent shape of the endoprosthesis. Byselecting the chemical composition of the shape memory materialaccordingly, a specific switching temperature can be fixed beforehand.

This being the case, the switching temperature is set so that it fallswithin the range of room temperature and the body temperature of thepatient. This is of particular advantage in applications where themedical device is to be implanted in a patient's body. Accordingly, whenimplanting the medical device, it is merely necessary to ensure that theinstrument is not heated and thus triggers the shape memory effect ofthe endoprosthesis material until it is in the implanted state on thepatient's body (36° C.).

Preferred embodiments of an endoprosthesis of a medical device proposedby the invention will be described in more detail below with referenceto the appended drawings.

Of these:

FIG. 1 a illustrates a first, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst predefined mode in which the medical device is in its collapsedstate;

FIG. 1 b shows the endoprosthesis illustrated in FIG. 1 a but in a statebetween its first pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 1 c shows the endoprosthesis illustrated in FIG. 1 a but in itssecond mode in which the medical device is in its expanded state;

FIG. 1 d shows a first, preferred embodiment of the medical deviceproposed by the invention in its expanded state, with an endoprosthesisof the type illustrated in FIG. 1 c with a heart valve prosthesisattached to it and opened out;

FIG. 1 e is a flat projection of a cutting pattern which can be used forthe production of the first, preferred, self-expandable endoprosthesisin order to cut the endoprosthesis illustrated in FIG. 1 a integrallyfrom a metal tube;

FIG. 2 a shows a second, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itscollapsed state;

FIG. 2 b shows the endoprosthesis illustrated in FIG. 2 a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 2 c shows the endoprosthesis illustrated in FIG. 2 a in its secondmode in which the medical device is in its expanded state;

FIG. 2 d illustrates a second preferred embodiment of the medical deviceproposed by the invention in its expanded state, with an endoprosthesisof the type illustrated in FIG. 2 c and a heart valve prosthesisattached to it and opened out;

FIG. 2 e is a flat projection of a cutting pattern which can be used forthe production of the second preferred, self-expandable endoprosthesisin order to cut the endoprosthesis illustrated in FIG. 2 a integrallyfrom a metal tube;

FIG. 3 a shows a third, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itscollapsed state;

FIG. 3 b shows the endoprosthesis illustrated in FIG. 3 a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 3 c shows the endoprosthesis illustrated in FIG. 3 a in its secondmode in which the medical device is in its expanded state;

FIG. 3 d illustrates a third preferred embodiment of the medical deviceproposed by the invention in its expanded state, with an endoprosthesisof the type illustrated in FIG. 3 c and a heart valve prosthesisattached to it and opened out;

FIG. 3 e is a flat projection of a cutting pattern which can be used forthe production of the third preferred, self-expandable endoprosthesis inorder to cut the endoprosthesis illustrated in FIG. 3 a integrally froma metal tube;

FIG. 4 a shows a fourth, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itscollapsed state;

FIG. 4 b shows the endoprosthesis illustrated in FIG. 4 a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 4 c shows the endoprosthesis illustrated in FIG. 4 a in its secondmode in which the medical device is in its expanded state;

FIG. 4 d illustrates a fourth preferred embodiment of the medical deviceproposed by the invention in its expanded state, with an endoprosthesisof the type illustrated in FIG. 4 c and a heart valve prosthesisattached to it and opened out;

FIG. 4 e is a flat projection of a cutting pattern which can be used forthe production of the fourth, preferred, self-expandable endoprosthesisin order to cut the endoprosthesis illustrated in FIG. 4 a integrallyfrom a metal tube;

FIG. 5 a shows a fifth preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itscollapsed state;

FIG. 5 b shows the endoprosthesis illustrated in FIG. 5 a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 5 c shows the endoprosthesis illustrated in FIG. 5 a in its secondmode in which the medical device is in its expanded state;

FIG. 5 d illustrates a fifth preferred embodiment of the medical deviceproposed by the invention in its expanded state, with an endoprosthesisof the type illustrated in FIG. 5 c and a heart valve prosthesisattached to it and opened out;

FIG. 5 e is a flat projection of a cutting pattern which can be used forthe production of the fifth, preferred, self-expandable endoprosthesisin order to cut the endoprosthesis illustrated in FIG. 5 a integrallyfrom a metal tube;

FIG. 6 a shows a sixth preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pro-determined mode in which the medical device is in itscollapsed state;

FIG. 6 b shows the endoprosthesis illustrated in FIG. 6 a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 6 c shows the endoprosthesis illustrated in FIG. 6 a in its secondmode in which the medical device is in its expanded state;

FIG. 6 d illustrates a sixth preferred embodiment of the medical deviceproposed by the invention in its expanded state, with an endoprosthesisof the type illustrated in FIG. 6 c and a heart valve prosthesisattached to it and opened out;

FIG. 6 e is a flat projection of a cutting pattern which can be used forthe production of the sixth, preferred, self-expandable endoprosthesisin order to cut the endoprosthesis illustrated in FIG. 6 a integrallyfrom a metal tube;

FIG. 7 a shows a seventh, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itscollapsed state;

FIG. 7 b shows the endoprosthesis illustrated in FIG. 7 a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 7 c shows the endoprosthesis illustrated in FIG. 7 a in its secondmode in which the medical device is in its expanded state;

FIG. 7 d illustrates a seventh preferred embodiment of the medicaldevice proposed by the invention in its expanded state, with anendoprosthesis of the type illustrated in FIG. 7 c and a heart valveprosthesis attached to it and opened out;

FIG. 7 e is a flat projection of a cutting pattern which can be used forthe production of the seventh preferred, self-expandable endoprosthesisin order to cut the endoprosthesis illustrated in FIG. 7 a integrallyfrom a metal tube;

FIG. 8 a shows an eighth, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itscollapsed state;

FIG. 8 b shows the endoprosthesis illustrated in FIG. 8 a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 8 c shows the endoprosthesis illustrated in FIG. 8.a in its secondmode in which the medical device is in its expanded state;

FIG. 8 d illustrates an eighth preferred embodiment of the medicaldevice proposed by the invention in its expanded state, with anendoprosthesis of the type illustrated in FIG. 8 c and a heart valveprosthesis attached to it and opened out;

FIG. 8 e is a flat projection of a cutting pattern which can be used forthe production of the eighth preferred, self-expandable endoprosthesisin order to cut the endoprosthesis illustrated in FIG. 8 a integrallyfrom a metal tube;

FIG. 9 a shows a ninth, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itscollapsed state;

FIG. 9 b is a perspective side view of a connecting web between an endportion of a positioning arch and an end portion of an associatedretaining arch of the endoprosthesis illustrated in FIG. 9 a in itssecond mode in which the medical device is in its expanded state;

FIG. 9 c is a perspective side view of a positioning arch and theassociated retaining arch of the endoprosthesis illustrated in FIG. 9 ain its second mode in which the medical device is in its expanded state;

FIG. 9 d is a perspective plan view of the distal region of theendoprosthesis illustrated in FIG. 9 a in its second mode in which themedical device is in its expanded state;

FIG. 9 e is a flat projection of a cutting pattern which can be used forthe production of the ninth preferred embodiment of the self-expandableendoprosthesis in order to cut the endoprosthesis illustrated in FIG. 9a integrally from a metal tube;

FIG. 10 is a flat projection of a cutting pattern which can be used forthe production of another preferred embodiment of the self-expandableendoprosthesis in order to cut an endoprosthesis integrally from a metaltube;

FIG. 11 shows another preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itssecond mode in which the medical device is in its expanded state;

FIG. 12 a is a schematic view intended to illustrate one possibleimplantation operation of the medical device proposed by this invention;and

FIG. 12 b is a schematic view of the medical device proposed by theinvention in the implanted state.

A first preferred embodiment of the self-expandable endoprosthesis 1 forthe medical device proposed by the invention will be described first ofall with reference to FIG. 1 a to 1 e. FIG. 1 a illustrates theendoprosthesis 1 in its first pre-definable mode in which the medicaldevice (not explicitly illustrated) is in a collapsed state and cantherefore be introduced into a patient's body with minimal invasion bymeans of a catheter system. FIG. 1 c illustrates the endoprosthesis 1 inits second mode in which the medical device is in its expanded state.FIG. 1 b illustrates the endoprosthesis 1 in a state between the firstmode (see FIG. 1 a) and the second mode (see FIG. 1 c). FIG. 1 dillustrates a first preferred embodiment of the medical device proposedby the invention in its expanded state with an endoprosthesis of thetype illustrated to FIG. 1 c and a heart valve prosthesis attached to itand secured.

The endoprosthesis 1 based on the first preferred embodiment isdistinctive due to the fact that it has a structure which is cutintegrally from a metal tube. The cutting pattern used to produce thestent design is illustrated in a flat projection in FIG. 1 e.Specifically, the endoprosthesis 1 comprises a total of threepositioning arches 10, which assume the function of automaticallypositioning the medical device in the patient's aorta. The positioningarches 10 have a rounded head portion 12, which engages in the pocketsof the insufficient heart valve to be replaced by the medical devicewhen the medical device is positioned at the implantation site.Providing three positioning arches 10 in total ensures that therequisite positioning accuracy can be obtained in the direction ofrotation.

The head portions 12 of the positioning arches 10 pointing respectivelytowards the proximal end 3 of the endoprosthesis 1 are appropriatelyrounded so that the vessel wall is not damaged when the positioningarches 10 engage in the pockets of the heart valve to be replaced.Extending from the head portion 12 of the positioning arch 10 to thedistal end 2 of the endoprosthesis 1 are two positioning webs or arms 11in total for each positioning arch 10, which merge into an eye-shapedelement 30 at the distal end 2 of the endoprosthesis 1. This eye-shapedelement 30 serves as a fixing means for attaching the endoprosthesis 1and hence the medical device to an introduction catheter system.

Specifically, the respective fixing eyes 30 are disposed between the twoarms 11 of two mutually adjacent positioning arches 10. Opening into thetransition portion 13 between the two arms 11 of two mutually adjacentpositioning arches 10 incorporating the fixing eye 30 is a connectingweb 15 extending essentially in the longitudinal direction of theendoprosthesis 1. At the proximal end, the connecting web 15 merges intothe respective retaining arms 21 of two mutually adjacent retainingarches 20.

As a result of this stent design, an axially symmetrical structure isobtained, whereby a retaining arch 20 is associated with eachpositioning arch 10. The endoprosthesis 1 in the preferred embodimentillustrated in FIGS. 1 a to 1 c therefore has a total of three retainingarms 20, which form the base for a retaining segment of theendoprosthesis 1 for accommodating a heart valve prosthesis 40(illustrated in FIG. 1 d, for example). Providing the respectiveconnecting webs 15 between the distally lying transition portions 23 oftwo mutually adjacent retaining arches 20 and the transition portions 13of two mutually adjacent positioning arches 10 results in a stentstructure whereby the respective arms 11 of a positioning arch 10 extendessentially parallel with the respective arms 21 of a retaining arch 21associated with the positioning arch 10.

When the endoprosthesis 1 is in the state illustrated in FIG. 1 a inwhich it assumes its first mode, the respective arms 11 of thepositioning arches 10 directly bound the respective arms 21 of theassociated retaining arches 20.

Particular attention should be paid to FIG. 1 c in which theendoprosthesis 1 based on the first preferred embodiment is illustratedin its second mode. Particularly worth mentioning in respect of thisdiagram is the fact that every positioning arch 10 and its associatedretaining arch 20 has an essentially U-shaped or V-shaped structurewhich is closed towards the proximal end 3 of the endoprosthesis 1.Specifically, every positioning arch 10 is cut from the material portionof the metal tube which is accommodated in the essentially U-shaped orV-shaped structure of the associated retaining arch 20, as may be seenfrom the cutting pattern illustrated in FIG. 1 e.

As may be seen by comparing FIGS. 1 a and 1 c, during the transitionfrom the first mode into the second mode, the endoprosthesis becomesshorter in the longitudinal direction whilst the cross-sectionsimultaneously becomes wider, in particular at the distal and theproximal retaining regions 2, 3. When the endoprosthesis 1 is in theexpanded state, the respective positioning arches 10 are specificallyopened out to a more pronounced degree in the radial direction than isthe case at the distal retaining region 2 of the stent 1. Thepositioning arches 10 which assume the function of positioning themedical device in the implanted state by engaging in the pockets of theold heart valve to be replaced can therefore project farther out in theradial direction and can be inserted in the heart valve pockets of theheart valve to be replaced in a particularly easy manner.

FIG. 1 d illustrates a first preferred embodiment of the medical deviceproposed by the invention in its expanded state, with an endoprosthesis1 of the type illustrated in FIG. 1 c and a heart valve prosthesis 40attached to with the aid of a thread 41 and opened out. As illustrated,opening out the proximal retaining region 3 of the endoprosthesis 1 inwhich the heart valve prosthesis 40 is disposed causes the heart valveprosthesis 40 to open out, whilst a radial force is simultaneouslyapplied to the vessel wall (not illustrated) by the proximal endportions 22 of the retaining arches 21, thereby affording a reliableseal of the heart valve prosthesis 40 with respect to the vessel wall.

Although the force exerted by the retaining arches 21 in the radialdirection onto the vessel wall causes the medical device to be securedat the implantation site to a certain extent, the distal retainingregion 2 is expanded by a further 10% to 25% in the radial directionthan is the case at the proximal retaining region 3 of theendoprosthesis 1 when the medical device is in the expanded state inorder to obtain a permanently stable implantation of the medical device,especially in view of the unavoidable peristaltic movement of the vesselwall and the relatively high fluid pressures which prevail. As a result,a slightly concave shape is imparted to the endoprosthesis 1, whichtapers in the direction of the proximal retaining region 3 of theendoprosthesis 1, thereby ensuring that the medical device is firmlyanchored in the vessel due to the distal retaining region 2 of theendoprosthesis 1 pressing against the vessel wall.

In the embodiment illustrated, the respective arms 21 of the retainingarches 20 have uninterrupted slots or elongate holes 24, the purpose ofwhich is to enable or assist expansion of the endoprosthesis 1 from thecollapsed state into the expanded state, because these slots or elongateholes 24 make it easy to widen the cross-section of the stent 1 whilstsimultaneously reducing its length. Naturally, however, it would also beconceivable for these slots or elongate holes 24 to accommodate a thread41 or similar used to attach the heart valve prosthesis 40 (illustratedin FIG. 1 d) to the proximal region 3 of the endoprosthesis 1.

The solution proposed by the invention is a medical device of a modulardesign essentially comprising the two separately manufacturedcomponents, endoprosthesis 1 and heart valve prosthesis 40, and theendoprosthesis 1 assumes the function of positioning and securing theheart valve prosthesis 40 in the patient's aorta. It may be preferableif the two components (endoprosthesis 1 and heart valve prosthesis 40)are not connected to one another until immediately prior to performingthe surgical intervention; this is of advantage in terms of transportingand storing the endoprosthesis 1 as such since the endoprosthesis 1 is arelatively robust component from a mechanical point of view and inparticular can be stored for a longer period. This applies in particularif the endoprosthesis 1 is stored in its second mode, i.e. in theexpanded state, and is not switched to its first (collapsed) mode untilimmediately prior to undertaking the surgical intervention.

The state of the endoprosthesis 1 illustrated in FIG. 1 a in which theendoprosthesis 1 is in its first mode and the medical device is in itscollapsed state is the so-called “temporary” mode of the endoprosthesisstructure made from a memory shape material. When an external stimulusacts on the endoprosthesis body illustrated in FIG. 1 a, the shapememory effect is triggered and the fixed permanent shape memorisedduring production of the endoprosthesis 1 illustrated in FIG. 1 c isrestored. This external stimulus is preferably a settable switchingtemperature and the body must be heated to a temperature higher than theswitching temperature in order to trigger the shape memory effect andthus restore the memorised permanent shape of the endoprosthesis 1. Byselecting the chemical composition of the material used for theendoprosthesis 1 accordingly, a specific switching temperature can befixed beforehand; in the case of the preferred embodiment of thesolution proposed by the invention, it lies in a range of between 20° C.and the body temperature of the patient.

When the medical device is being implanted, it would therefore beconceivable for the medical device to be cooled accordingly during theintroduction process. When the medical device has been moved to thedesired implantation site, in other words in front of the native heartvalve, preferably by means of an appropriate introduction system,cooling can be interrupted so that the endoprosthesis 1 of the medicaldevice is heated to the body temperature (36° C.) of the patient,thereby triggering the shape memory effect of the endoprosthesismaterial. Having triggered the self-expanding property of theendoprosthesis 1, radial forces are generated which act on theindividual components of the endoprosthesis 1 and in particular on therespective positioning arches 10, 11 and retaining arches 20, 21 of theendoprosthesis 1. Since the endoprosthesis 1 of the medical device isstill disposed in the introduction catheter system as before, the radialforces which build up once the critical switch temperature is exceededand act on the individual components of the endoprosthesis 1 are stillcompensated by the introduction port of the introduction catheter systemso that—in spite of the shape memory effect having been triggered—theendoprosthesis 1 of the medical device is forcibly retained in its first(collapsed) mode.

By releasing the endoprosthesis 1 from the introduction catheter systemin appropriate steps, it is then possible to release the positioningarches 10, 11 of the endoprosthesis 1 through the introduction port ofthe introduction catheter system first, as a result of which it opens updue to the radial forces acting in the radial direction. The openedpositioning arches 10, 11 can then be positioned in the pockets of thenative heart valve.

The remaining components of the endoprosthesis 1 and the medical devicecan then be released through the introduction port of the introductioncatheter system. As this happens, the retaining arches 20, 21 open inthe radial direction and the heart valve prosthesis 40 attached to theretaining arches 20, 21 by means of a thread 41, etc., for example, thusunfolds in the manner of an umbrella. The radial forces acting on theretaining arches 20, 21 but also on the distal retaining region 2 of theendoprosthesis 1 cause the endoprosthesis 1 to be pressed in the radialdirection against the vessel wall, which guarantees a reliable anchoringof the medical device at the implantation site on the one hand andensures a reliable seal of the heart valve prosthesis 40 at the proximalretaining region 3 of the endoprosthesis 1 on the other hand.

FIGS. 2 a to 2 c illustrate a second preferred embodiment of aself-expandable endoprosthesis 1 for the medical device proposed by theinvention in its first, pre-definable mode (see FIG. 2 a) in its secondpre-definable mode (see FIG. 2 c) as well as in a state in between (seeFIG. 2 b).

FIG. 2 d illustrates a second preferred embodiment of the medical deviceproposed by the invention in its expanded state with an endoprosthesisof the type illustrated in FIG. 2 c and a heart valve prosthesis 40attached to it and opened out. A flat projection of a cutting patternwhich may be used for the production of the second preferred embodimentof the self-expandable endoprosthesis is illustrated in FIG. 2 e. Thiscutting pattern is suitable for cutting the endoprosthesis illustratedin FIG. 2 a integrally from a metal tube.

The endoprosthesis 1 based on the second preferred embodimentessentially corresponds to the first preferred embodiment describedabove with reference to FIGS. 1 a to 1 e. The second embodiment differsfrom the first preferred embodiment of the endoprosthesis due to thefact that the respective arms 11 of the adjacent positioning arches 10are joined indirectly via a connecting, web 16 extending essentially inthe longitudinal direction of the endoprosthesis 1 to the fixing eye 30,and the respective arms 21 of the retaining arches 20 associated withthe adjacent positioning arches 10 are indirectly joined via aconnecting web 15 extending essentially in the longitudinal direction ofthe endoprosthesis 1 to the fixing eye 30. Specifically, the connectingweb 15 of the retaining arches 20 merges into the connecting web 16 ofthe positioning arches 10 at the end portion 13 of the positioningarches 10. By selecting the respective lengths of the two connectingwebs 15 and 16 accordingly, therefore, the overall length of the stent 1can be adjusted in an easy manner.

The third preferred embodiment of a self-expandable endoprosthesis forthe medical device proposed by the invention illustrated in FIGS. 3 a to3 c essentially corresponds to the first preferred embodimentillustrated in FIGS. 1 a to 1 c; the difference, however, is that in thethird preferred embodiment, the fixing eyes 30 disposed between twoadjacent positioning arches 10 are provided with barbs 17, therespective tips of which point in the direction of the proximal end 3 ofthe endoprosthesis 1. With this modification to the design of the heartvalve-stent 1 based on the first preferred embodiment, therefore,additional anchoring is provided for the system to prevent the stent 1from being dislocated in the direction of the left ventricle.

FIG. 3 d illustrates a third preferred embodiment of the medical deviceproposed by the invention in its expanded state with an endoprosthesisof the type illustrated in FIG. 3 c and a heart valve prosthesis 40attached to it and opened out. This diagram essentially corresponds tothat of FIG. 1 d; the exception, however, is the fact that the barbelements 17 described above are provided on the respective fixing eyes30.

A flat projection of a cutting pattern which may be used for theproduction of the third preferred embodiment of the self-expandableendoprosthesis 1 is illustrated in FIG. 3 e. This cutting pattern issuitable for cutting the endoprosthesis illustrated in FIG. 3 aintegrally from a metal tube. FIG. 4 a to FIG. 4 c illustrate a fourthpreferred embodiment of a self-expandable endoprosthesis 1 for themedical device proposed by the invention. A fourth preferred embodimentof the medical device proposed by the invention is illustrated in itsexpanded state with an endoprosthesis in FIG. 4 c and an opened outheart valve prosthesis 40 attached to it is illustrated in FIG. 4 d,whilst FIG. 4 e illustrates a flat projection of a cutting pattern,which may be used for the production of the fourth preferred embodimentof the self-expandable endoprosthesis 1. The cutting pattern illustratedin FIG. 4 e is specifically suitable for cutting the endoprosthesisillustrated in FIG. 4 a integrally from a metal tube.

The fourth preferred embodiment of the self-expandable prosthesis 1corresponds to a combination of the second and third preferredembodiments described above. Specifically, the respective arms 11 of theadjacent positioning arches 10 are indirectly joined via the connectingweb 16 extending essentially in the longitudinal direction of theendoprosthesis to the fixing eye 30, whilst barbs 17 are provided on therespective fixing eyes 30, the tips of which point in the direction ofthe proximal end 3 of the endoprosthesis 1. The advantages which can beachieved as a result of the features provided on the fourth preferredembodiment were described above and will not be reiterated at thisstage.

The fifth preferred embodiment of a self-expandable endoprosthesis 1 anda medical device proposed by the invention illustrated in FIG. 5 a toFIG. 5 e essentially corresponds to the first preferred embodimentdescribed with reference to FIG. 1 a to FIG. 1 e, except that in thisinstance, the respective retaining arches 21 of the endoprosthesis 1 areprovided with reinforcing portions 26, which interrupt the slots 24extending in the longitudinal direction of the retaining arches 21. Thepurpose of these reinforcing portions 26 is to open out the individualcomponents of the retaining arches 21, and in particular to break theanchoring support 25 radially out of the retaining arches 20.Accordingly, a retaining portion for the stent 1 can be obtained withthe reinforcing portions 26, which has no components which might explantthe medical device when it is in the expanded state.

FIG. 5 e illustrates a flat projection of a cutting pattern which may beused for production of the fifth preferred embodiment of theself-expandable endoprosthesis 1 in order to cut the endoprosthesis 1illustrated in FIG. 5 a integrally from a metal tube.

The sixth preferred embodiment of the self-expandable endoprosthesis andthe medical device proposed by the invention illustrated in FIGS. 6 a to6 e corresponds to a combination of the second preferred embodimentillustrated in FIGS. 2 a to 2 e and the fifth preferred embodimentdescribed above with reference to FIGS. 5 a to 5 e. Specifically,therefore, the endoprosthesis 1 based on the second preferred embodimentis provided with additional anchoring portions 26 at the respectiveretaining arches 21, which interrupt the slots 24 extending in thelongitudinal direction of the retaining arches 21.

The seventh preferred embodiment of the endoprosthesis 1 and the medicaldevice proposed by the invention illustrated in FIGS. 7 a to 7 ecorresponds to a combination of the third and fifth embodimentsdescribed above, in which case the respective fixing eyes 30 areprovided with barbs 17 and the respective retaining arches 21 areprovided with reinforcing portions 26.

The eighth preferred embodiment of the self-expandable endoprosthesisand the medical device proposed by the invention illustrated in FIGS. 8a to 8 e corresponds to a combination of the fourth and fifthembodiments, in which case the respective retaining arches 21 areprovided with reinforcing portions 26 and the fixing eyes 30 providedwith barbs 17 are connected to the respective arms 11 of the adjacentpositioning arches 10 by means of a connecting web 16 extendingessentially in the longitudinal direction of the endoprosthesis 1.

The ninth preferred embodiment of the self-expandable endoprosthesis forthe medical device proposed by the invention illustrated in FIGS. 9 a to9 d is of a slightly modified shape compared with the first embodiment(see FIGS. 1 a to 1 c). The endoprosthesis 1 based on the ninthembodiment is illustrated in its first pre-defined mode in FIG. 9 a.FIGS. 9 b and 9 c respectively show a perspective side view of theendoprosthesis 1 based on the ninth embodiment in its second mode.Specifically, the connecting web 15 between the end portion 13 of apositioning arch 10, 11 and the end portion 23 of an associatedretaining arch 20, 21 is illustrated in FIG. 9 b. FIG. 9 c, on the otherhand, illustrates the positioning arches 10, 11 and the associatedretaining arches 20, 21 of the endoprosthesis 1 illustrated in FIG. 9 a.

FIG. 9 e illustrates a flat projection of a cutting pattern which may beused to produce the ninth preferred embodiment of the self-expandableendoprosthesis in order to cut the endoprosthesis illustrated in FIG. 9a integrally from a metal tube.

Unlike the first embodiment, the respective head portions 12 of thepositioning arches 10 pointing towards the proximal end 3 of theendoprosthesis are of a slightly wider design at the proximal end in theninth embodiment of the endoprosthesis 1. Although the head portions 12of the positioning arches 10 have a slightly rectangular in shapecompared with the first embodiment, all the respective corners of thehead portions 12 are rounded so that the vessel wall is not damaged whenthe positioning arches 10 engage in the pockets of the heart valve to bereplaced. The advantage of the slightly wider design of the headportions 12 of the positioning arches 10 is that the positioning arches10 can be placed in the pockets of the native heart valve with thesmallest possible clearance during the implantation operation, therebyenabling even more accurate positioning of the medical device at theimplantation site.

As with the embodiments described above, a total of two positioning websor arms 11 extend from the head portion 12 of the positioning arches 10to the distal end 2 of the endoprosthesis 1 for every positioning arch10 in the ninth embodiment of the endoprosthesis 1, which merge at thedistal end 2 of the endoprosthesis 1 into an eye-shaped element 30. Thiseye-shaped element 30 serves as a fixing means for attaching theendoprosthesis 1 and hence the medical device to an introductioncatheter system.

Specifically in the case of the ninth embodiment of the endoprosthesis1, the respective fixing eyes 30 are disposed between the two arms 11 oftwo mutually adjacent positioning arches 10. The connecting web 15extending essentially in the longitudinal direction of theendoprosthesis 1 opens into the transition portion 13 between the twoarms 11 of two mutually adjacent positioning arches 10 where the fixingeye 30 is formed. At the proximal end of the connecting web 15, thelatter merges into the respective retaining arms 21 of two mutuallyadjacent retaining arches 20. This design is illustrated particularlyclearly in FIG. 9 d, which shows a perspective plan view of the distalregion of the endoprosthesis illustrated in FIG. 9 a in its second mode.

By contrast with the embodiments described above, the respectiveretaining arms 21 of the retaining arches 20 on the transition portion23 between the two arms 21 of two mutually adjacent retaining arches 20are not provided with slots or elongate holes 24 in the ninth embodimentof the endoprosthesis 1. Due to the fact that only one arm web 21actually opens into the transition portion 23 between the two arms 21 oftwo mutually adjacent retaining arches 20 for each retaining arch, thereare advantageously no components belonging to the retaining arches 20which project out from the respective retaining arches 20 in the radialdirection when the endoprosthesis 1 is in the expanded state (see FIG. 9b for example). Especially when the endoprosthesis 1 is in the expandedstate, no barb portion such as usually extends through the slots 24projects out in the radial direction at the transition portions 23between the two arms 21 of two mutually adjacent retaining arches 20,the tip of which points in the direction of the distal retaining region2 of the endoprosthesis 1. Due to the fact that a barb portion of thistype is dispensed with in the ninth embodiment, the endoprosthesis 1 canbe explanted particularly easily and removed from the patient's bodyagain.

Although the ninth embodiment of the endoprosthesis 1 does not haveslots or elongate holes 24 at the respective transition portions 23between the two arms 21 of two mutually adjacent retaining arches 20,the respective retaining arms 21 of the endoprosthesis 1 havereinforcing portions 26, which are respectively provided on portions ofthe retaining arms 21 that are not congruent with the transitionportions 23 between the two arms 21 of two mutually adjacent retainingarches 20.

FIG. 10 illustrates a flat projection of a cutting pattern, which may beused for the production of another preferred embodiment of theself-expandable endoprosthesis 1 in order to cut an endoprosthesisintegrally from a metal tube. The cutting pattern illustrated in FIG. 9differs from the cutting pattern illustrated in FIG. 1 e due to the factthat the distally disposed slots 24 extending in the longitudinaldirection of the retaining arches 21 have been omitted from therespective retaining arches 21 on the one hand, and a bigger space 27 iscut from between the adjacent retaining arches 21 in order to save onmaterial on the other hand.

FIG. 11 illustrates another preferred embodiment of a self-expandableendoprosthesis 1 for an alternative design of the medical deviceproposed by the invention. Specifically, the endoprosthesis 1 of theother preferred embodiment illustrated in FIG. 11 has assumed its secondmode in which the medical device is in its expanded state and contains adifferent embodiment of the endoprosthesis 1 for the medical deviceproposed by the invention. Specifically, this is an endoprosthesis 1which is in its second mode, i.e. after triggering the shape memoryeffect.

The endoprosthesis 1 illustrated in FIG. 11 differs from theendoprosthesis 1 illustrated in FIG. 1 c due to the fact that in thecase of the stent 1 illustrated in FIG. 11, an interconnecting web 16extending essentially in the longitudinal direction of theendoprosthesis 1 is provided between the fixing eyes 30 and thetransition portion 13 between the positioning arms 11 of two adjacentpositioning arches 10, and the total length of the endoprosthesis 1 andhence the medical device is made longer. In order to ensure optimumability to manoeuvre the medical device in the collapsed state, however,it is of advantage if the endoprosthesis 1 has as short a longitudinalextension as possible, especially if the implantation route to the heartvalve leads through the arch of the aorta, in which case it is ofadvantage if the medical device is as short as possible (and theendoprosthesis 1 is also as short as possible) so that it can overcomethis bend.

The endoprosthesis 1 illustrated in FIG. 11 also differs from theendoprosthesis of the embodiments described above due to the fact thatwhen the endoprosthesis 1 is in the expanded state, a barb portion 25projects through the slots 24 in the radial direction at the respectivetransition portions 23 between the two arms 21 of two mutually adjacentretaining arches 20, the tip of which points in the direction of thedistal retaining region 2 of the endoprosthesis 1.

A more detailed description will be given below with reference to FIGS.12 a ad 12 b, explaining how the medical device proposed by theinvention is used to treat a condition of heart valve insufficiency.

The medical device proposed by the invention, and in particular theendoprosthesis 1 with the heart valve prosthesis 40 contained in it, isdesigned to be introduced into the patient's body either backwards ortransapically, i.e. coming from the heart apex, via a special catheter,positioned percutaneously orthotopically in vivo and assume the functionof an insufficient or narrowed heart valve. FIG. 12 a provides aschematic illustration of one possible implantation operation for themedical device proposed by the invention, whereby the medical device inthis instance is introduced into the patient's body backwards using aspecial catheter. FIG. 12 b provides a schematic view of the medicaldevice proposed by the invention in the implanted state.

In the case of the implantation route illustrated in FIG. 12 a, thespecial catheter system, which is not specifically illustrated,containing the medical device with the heart valve prosthesis 40 and theendoprosthesis 1 serving as an anchoring stent are introduced bypuncturing the A. femoris communis (inguinal artery). This cathetersystem is preferably moved forward to the aortal valve position assistedby angiographic (vessel display) and echocardiographic (ultrasound)control, where the actual heart valve implantation then takes place.

Alternatively, a special catheter system can be pushed transapicallyfrom the heart apex through the left ventricle to the aortal valve,where a similar implantation of the endoprosthesis 1 with the heartvalve prosthesis 40 is possible using a catheter tube modifiedaccordingly.

As the special catheter system is being fed forwards, the medical deviceis preferably appropriately cooled, for example by rinsing the specialcatheter system with an appropriate coolant, such as a salt solution.When the medical device has been moved forward to the desiredimplantation site, cooling is interrupted, as a result of which theendoprosthesis 1 of the medical device is warmed to the body temperature(36° C.) of the patient, thereby triggering the shape memory effect ofthe endoprosthesis material.

Due to the triggering of the self-expanding property of theendoprosthesis 1, radial forces develop which act on the individualcomponents of the endoprosthesis 1 and in particular on the respectivepositioning arches 10, 11 and retaining arches 20, 21 of theendoprosthesis 1. Since the endoprosthesis 1 of the medical device isstill disposed in the introduction catheter system as before, the radialforces which develop once the critical switching temperature is exceededand act on the individual components of the endoprosthesis 1 are stillcompensated by the introduction port of the introduction catheter systemso that—in spite of the shape memory effect having been triggered—theendoprosthesis 1 of the medical device is forcibly held in its first(collapsed) shape.

By releasing the endoprosthesis 1 from the introduction catheter systemin appropriate steps, the positioning arches 10, 11 of theendoprosthesis 1 are then moved out though the introduction port of theintroduction catheter system. The positioning arches 10, 11 open out dueto the radial forces acting in the radial direction. The openedpositioning arches 10, 11 are then positioned in the pockets 50 of thenative heart valve 51.

The other components of the endoprosthesis 1 and the medical device arethen released through the introduction port of the introduction cathetersystem. As illustrated in FIG. 12 b, the retaining arches 20, 21 open inthe radial direction at the same time and thus cause the heart valveprosthesis 40 attached to the to the retaining arches 20, 21 by means ofa thread 41, etc., for example, top open out in the manner of anumbrella. However, the radial forces acting on the retaining arches 20,21 also act on the distal retaining region 2 of the endoprosthesis 1,causing the endoprosthesis 1 to be pressed in the radial directionagainst the vessel wall, which on the one hand guarantees a reliableanchoring of the medical device at the implantation site and on theother hand ensures a reliable seal of the heart valve prosthesis 40 atthe proximal retaining region 3 of the endoprosthesis 1.

When the medical device is in the implanted state illustrated in FIG. 12b, the heart valve prosthesis 40 is opened out at the proximal retainingregion 3 of the endoprosthesis 1 whilst the old (insufficient) heartvalve 51 is pressed against the vessel wall due to the self-expandingproperty of the endoprosthesis 1. The distal retaining region of theendoprosthesis 1 affords additional mechanical support for the systemand reliable anchoring.

As may specifically be seen from FIG. 12 b, when the endoprosthesis 1 isin the expanded state, the respective positioning arms 21 of thepositioning arches 20 locate in the pockets of the diseased heart valveand thus guarantee secure and error-free positioning of the medicaldevice. The pocket flaps of the diseased heart valve are clamped betweenthe positioning arches 10 and the retaining arches 20 due to theexpansion of the endoprosthesis 1, which further assists in achievingoptimum positioning and a stable anchoring of the heart valve prosthesis40 disposed at the proximal retaining region 3 of the endoprosthesis 1.Optimum lateral sealing of the implanted valve prosthesis 40 isguaranteed at the same time.

The system is afforded additional mechanical support and reliableanchoring can also be achieved by providing barbs 17 on the fixing eyes30 disposed at the distal retaining region 2 of the endoprosthesis 1and/or by appropriate anchoring supports 25. When the endoprosthesis 1is in the expanded state, the anchoring supports 25 stand proud of theco-operating arm 21 of the retaining arches 20, and their tips point inthe direction of the distal end 2 of the endoprosthesis 1.

In principle, the special design of the endoprosthesis 1 offers thepossibility of gripping the endoprosthesis 1 subsequently by means ofthe fixing eyes 30 and collapsing the medical device by the longitudinalextension of the endoprosthesis 1 so that the medical device can beremoved from the patient's body again by means of a catheter tube.

Due to the modular integration of retaining elements (fixing eyes) onthe self-expandable endoprosthesis 1, it can also be explanted again bymeans of a special catheter once it has been implanted. To this end, thedistal retaining region 2 of the endoprosthesis 1 is pulled into acatheter by several retaining points using guide wires. This being thecase, in the reverse of the implantation operation, the endoprosthesis 1is pulled from its expanded state into the collapsed state and releasedfrom the anchoring in the pockets of the actual heart valve.

In summary, it remains to be said that the solution proposed by theinvention is based on a metal endoprosthesis 1 with a heart valveprosthesis which can be stitched to it or is stitched to it, designedfor use in treating diseases of the heart valve which make replacementof the old heart valve necessary. The heart valve stent 1(endoprosthesis) may be introduced in the inverted position and thuspositioned orthotopically in vivo percutaneously and assume the functionof the insufficient or defective native heart valve. The radial forcescreated due to the self-expanding property of the endoprosthesis 1guarantee reliable anchoring in the region of the aorta.

Specifically, a medical instrument comprising an endoprosthesis 1 forpositioning and securing a heart valve prosthesis in the aorta of thepatient is described, and a specially developed endoprosthesis 1 madefrom a base of Nitinol is provided as a means of accommodating a heartvalve prosthesis for implantation in the aorta. The ready-to-use medicaldevice proposed by the invention consists of the components comprisingthe self-expandable Nitinol stent 1 with the valve-supporting segment20, valve and system for introducing it to the desired site in the body.

In terms of design, the endoprosthesis 1 has three positioning archesfor positioning and fixing the medical device in the vessel of thepatient and retaining webs for accommodating/attaching the heart valveprosthesis by means of a thread, for example. From a functional point ofview, the endoprosthesis 1 exerts high radial forces in its second modeto ensure that the medical device is anchored in the aorta. Eyes 30 arepreferably provided on the distal retaining region of the endoprosthesis1 or medical device, which can be releasably engaged with correspondingcomponents of an introduction catheter system.

The material used to trigger the shape memory effect of theendoprosthesis has a switching temperature between 20° C. and 36° C. andis preferably 22° C. In the cooled state, therefore, the medical devicecan be introduced into the patient's body by means of a 21F introductionsystem.

As regards the exact dimensions of the endoprosthesis 1, it is designedto accommodate heart valve prostheses with a valve diameter of 21 mm to25 mm, in which case the distal retaining region 2 of the endoprosthesis1 in particular has a diameter that is approximately 10% to 15% biggerthan this in order to ensure that the medical device is reliablyanchored.

The medical device proposed by the invention has an endoprosthesis whichis readily visible by X-ray, which can be achieved by applying markersat the proximal and/or distal region of the endoprosthesis if necessary.

The materials used for the endoprosthesis 1 are materials that have beentried and tested for implantation purposes, for example Nitinol andTantal. As regards the dimensions of the endoprosthesis, two differentstent sizes are currently preferred, which are set out in the tablebelow together with the diameter of the proximal retaining region andthe distal retaining region.

Diameter of the proximal Diameter of the distal Stent size retainingregion retaining region Stent No. 1 21 to 25 mm 32 to 34 mm Stent No. 226 to 31 mm 35 to 38 mm

By applying an appropriate finishing treatment, in particular tempering,other dimensions of the stent can be achieved—starting from the twocurrently preferred stent sizes.

The invention is not restricted to the features described in connectionwith the preferred embodiments illustrated in the drawings. Allcombinations of the features described in the specification would beconceivable.

1-21. (canceled)
 22. A method of treating a native heart valve, themethod comprising: expanding a plurality of first arches from acollapsed configuration to an expanded configuration while holding aplurality of second arches in a collapsed configuration, each first archbeing directly connected to an adjacent first arch; positioning theexpanded plurality of first arches radially outward of at least onenative leaflet of the native heart valve and radially inward of a vesselwall; after positioning the expanded plurality of first arches,expanding the plurality of second arches from the collapsedconfiguration to an expanded configuration, the plurality of secondarches being coupled to a prosthetic valve; and engaging the at leastone native leaflet with at least one of the plurality of first archesand at least one of the plurality of second arches; wherein theprosthetic valve is not attached to the plurality of first arches. 23.The method of claim 22, further comprising introducing the plurality offirst arches into a femoral artery and advancing the plurality of firstarches to a position adjacent the native heart valve.
 24. The method ofclaim 22, further comprising introducing the plurality of second archesinto a femoral artery and advancing the plurality of second arches to aposition adjacent the native heart valve.
 25. The method of claim 22,wherein the plurality of first arches self-expand.
 26. The method ofclaim 22, wherein each first arch has an apex pointing towards a nativeheart.
 27. The method of claim 22, wherein each second arch has an apexpointing towards a native heart.
 28. The method of claim 22, wherein adistal portion of at least one of the first arches includes anattachment element, the method further comprising releasing theattachment element from a catheter.
 29. The method of claim 28, whereineach of three first arches includes an attachment element, the methodcomprising releasing each of the attachment elements from the catheter.30. The method of claim 22, wherein engaging the at least one nativeleaflet includes clamping the at least one native leaflet between atleast one of the plurality of first arches and at least one of theplurality of second arches.
 31. The method of claim 22, wherein engagingthe at least one native leaflet with at least one of the plurality offirst arches and at least one of the plurality of second arches anchorsthe plurality of first arches and the plurality of second archesrelative to the native heart valve.
 32. The method of claim 22, whereinthe prosthetic valve is fixedly attached to the plurality of secondarches.
 33. The method of claim 22, wherein the plurality of firstarches and the plurality of second arches are components of an integralstructure.
 34. A method of treating a native heart valve, the methodcomprising: expanding a plurality of first arches from a collapsedconfiguration to an expanded configuration while holding a plurality ofsecond arches in a collapsed configuration; positioning the expandedplurality of first arches radially outward of at least one nativeleaflet of the native heart valve and radially inward of a vessel wall;after positioning the expanded plurality of first arches, expanding theplurality of second arches from the collapsed configuration to anexpanded configuration, the plurality of second arches being coupled toa prosthetic valve; and clamping the at least one native leaflet betweenat least one of the plurality of first arches and at least one of theplurality of second arches.
 35. The method of claim 34, furthercomprising pressing at least a portion of the at least one nativeleaflet against the vessel wall.
 36. The method of claim 34, wherein theplurality of first arches comprises a shape memory material.
 37. Themethod of claim 34, wherein the plurality of first arches includes atleast three first arches.
 38. A method of treating a native heart valve,the method comprising: expanding a plurality of first arches from acollapsed configuration to an expanded configuration while holding aplurality of second arches and third arches in a collapsedconfiguration, each second arch and each third arch pointing in a samedirection; positioning the expanded plurality of first arches radiallyoutward of at least one native leaflet of the native heart valve andradially inward of a vessel wall; after positioning the expandedplurality of first arches, expanding the plurality of second arches andthird arches from the collapsed configuration to an expandedconfiguration, the plurality of second arches being coupled to aprosthetic valve; and engaging the at least one native leaflet with atleast one of the plurality of first arches and at least one of theplurality of second arches; wherein each second arch has an apex axiallyaligned with an apex of one of the third arches to define a spacetherebetween.
 39. The method of claim 38, wherein the plurality of thirdarches are proximal to the plurality of second arches.
 40. The method ofclaim 38, wherein the prosthetic valve is not connected to the pluralityof first arches or the plurality of third arches.
 41. The method ofclaim 38, wherein engaging the at least one native leaflet includesclamping the at least one native leaflet between at least one of theplurality of first arches and at least one of the plurality of secondarches.